1. Field of the Invention
This invention relates to a hullform configuration to improve efficiency and power of vessels or the like. In particular, the invention relates to improved performance for a Naval destroyer with a sonar dome positioned below the baseline of the hull.
2. Description of the Prior Art
Many different types of bulbous bow configuration have been contemplated in the past in attempting to minimize drag and wave resistances caused by a vessel moving through water, to increase speed and to save fuel. Weicker U.S. Pat. No. 3,455,262; Taylor et al. U.S. Pat. No. 3,946,687; Allen U.S. Pat. No. 4,003,325; Inui U.S. Pat. No. 4,359,010; Ingvason U.S. Pat. No. 4,550,673; Langenberg U.S. Pat. No. 4,843,989; Stanford U.S. Pat. No. 5,090,352; and Eckert U.S. Pat. No. 3,302,603, and Re 26,997, for instance, disclose different types of bulbous bow configuration for commercial vessels. In general, these bulbous bows extend in front of the bow, between the vessel baseline (BL) and the vessel waterline (DWL) and continue toward the hull thereof.
A Naval ship, such a high speed Naval destroyer DDG-51 Flight I with an AN/SQS-53C sonar dome (hereafter the Naval destroyer) of the U.S. Navy, in contrast, has a relatively large teardrop-shaped sonar dome at the bow for housing a sonar equipment. The sonar dome is situated below the ship baseline to minimize any interfering noise caused by flow of water. Generally, the sonar dome is located in free stream flow ahead of any noise sources, such as the bow wave breaking, and below the Naval destroyer baseline. It has been found that the sonar dome of that type which are situated below the ship baseline generally increases the drag resistance of the ship at low and cruise speeds, while reducing the drag resistance by 1-2% at the maximum speed.
The naval destroyer has a 466 ft LBP, a 60 ft beam, 20.688 ft draft, and a displacement of 8500 tons. The principle scaled body plan (scale factor of 20.2609) for the Naval destroyer, also known as DTMB Model 5422, is represented in FIG. 1, with the forward end of the sonar dome (SD) located at 4.5 ft ship scale forward of the forward perpendicular. FIG. 1 shows a conventional ship body plan. The reference lines DWL and BL represents the design waterline and the baseline, respectively. The length of the ship from the forward perpendicular to the transom is divided into twenty equally spaced stations. The distance between each station is 23.3 ft ship scale. Each of the numbers 0, 1/2, 1, 2, 4, 6, 8, 10, 11, 13, 14, 15, 16, 17, 18, 19 and 20 is a cross sectional configuration of the hull at that station.
The sonar dome typically has a much smaller effect on the wavemaking resistance of the ship than a bulbous bow which is located close to the waterline and has a much greater impact on the ship wavemaking resistance.
Commercial vessels, including some Naval ships without the sonar domes, on the other hand, may utilize bulbous bows of the type described in the above patents, but not in combination with a sonar dome. Prior to the present invention, a combination of a near surface bulbous bow and a below baseline sonar dome has not been contemplated because the sonar dome and the bulbous bow are in relatively close proximity to each other and thus were theorized to have been mutually exclusive. In other words, the sonar dome would have substituted for the bulbous bow and vice-versa, but not in combination.